2021 GMC Sierra 3500 Electrical system Problems
- Complaints
- 4about this part
- Share
- 20%of 20 total for the year
- Median mileage
- 26,000miles
- Trend
- Not enough dataFewer than 15 complaints, too few for a reliable trend.
NHTSA recorded 4 complaints about the electrical system of the 2021 GMC Sierra 3500, 20% of the 20 complaints for this model year. Where a mileage was given, the median is 26,000 miles.
Fewer than 15 complaints name this part, so treat the figures as a rough indication only.
Example complaints
Selected from NHTSA records; personal details are removed. They are consumer reports, not findings.
“When carrying the electronic key in my pocket the vehicle will lock/unlock presumably due to the remote contacting other items in the pocket. I have owned well over a dozen GM vehicles and never had this issue. I believe the remote design has the lock/unlock buttons too proud of the surrounding surface”
NHTSA complaint #11647111, filed 2025-03“Trailer brake wiring connection continually disconnectsthen reconnects some time later. Some periods of up to 10 minutes without having trailer braking power. Major safety issue when toeing fifth wheel trailer. We lost brakes going down steep grades. GMC is aware of issue, but has not provided a solution. Vehicle has been yo service shop with no resolution. Case has been opened with GMC.”
NHTSA complaint #11420443, filed 2021-06“The contact owns a 2021 GMC Sierra 3500. The contact stated that while his wife had the vehicle idling with the rear defroster activated, shortly afterwards, she observed smoke coming from the plastic on the rear sliding window. After a visual inspection, the contact's wife observed that the plastic was melting, prompting her to deactivate the rear defroster. No warning lights were illuminated. The vehicle was taken to the dealer, who was unable to determine the cause of the failure. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 26,000.”
NHTSA complaint #11685740, filed 2025-09, 26,000 miles“Multiple instances of diesel engine emissions system parts and software failure. While driving, towing or not, the DIC would randomly display a message that the DEF level is low and reduced speed will occur in x-amount of miles and that mileage would then begin a visible countdown on the DIC, sometimes much more quickly than the actual speed I was traveling. In other words, it might at first state 500 miles remaining, but then be counting down from 500 miles by one mile per second of time, or faster. …”
NHTSA complaint #11623109, filed 2024-11Related service bulletins
- 11024486May 16, 2025This bulletin advises the tech to inspect deeper into what may be to main cause of an engine failure.
- 11019017Apr 10, 2025This bulletin provides a procedure on how to check for a battery drain utilizing the Picoscope and how to measure the load on the system that may be causing a drain.
- 11017595Apr 3, 2025This service bulletin provides information on the proper Reflective High Temperature Heat and/or Insulating Tape to use for certain repairs, such as Wiring Harness Repairs.
- 11017244Mar 31, 2025The intent of this service bulletin is to identify aftermarket ALDL or DLC interface devices as potential sources for causing multiple customer concerns that do not have other…
- 11017255Mar 25, 2025This service bulletin helps diagnose/reduce possible CCND issues on Transfer Cases - Service 4WD on DIC, Intermittent Failures, Noise Concerns, Driveline/Steering…
- 11017207Mar 21, 2025This service bulletin provides information for dealers/technicians on Service Programming System (SPS) Error Codes E4398, E4399, E4401, E4403, M4404, M4413, M6954, M6955, E4414…
- 11017031Mar 12, 2025This service bulletin provides information to diagnose batteries that have set for a long period of time and/or cold weather climates and testing those batteries.
- 11014579Feb 19, 2025This technical bulletin provides repair information to correct a customer concern of Diagnostic Tips For Park Assist Off Message / Unwanted Or False Park Assist Alerts / No DTCs.
- 11014230Jan 31, 2025This bulletin advises the dealers to maintain the vehicle stock on hand by doing a full inspection on the vehicles before being sold (prepping) to the customer.
- 11014239Jan 29, 2025This service bulletin provides information on the Transport Mode Feature, also known as Logistics mode, which is used to increase the 12V Battery stand time of the vehicle during…
Electrical system: other model years
| Year | Complaints | Share of year |
|---|---|---|
| 2026 | 1 | 20% |
| 2025 | 3 | 18% |
| 2024 | 15 | 30% |
| 2023 | 4 | 14% |
| 2022 | 7 | 22% |
| 2021 | 4 | 20% |
| 2020 | 9 | 18% |
| 2019 | 3 | 23% |
| 2018 | 2 | 14% |
| 2017 | 3 | 23% |
| 2016 | 2 | 11% |
| 2015 | 6 | 19% |
| 2014 | 1 | 14% |
| 2013 | 1 | 7% |
| 2012 | 2 | 22% |
| 2011 | 2 | 10% |
| 2009 | 1 | 20% |
| 2008 | 1 | 4% |
| 2007 | 2 | 13% |
| 2005 | 3 | 13% |
| 2004 | 5 | 21% |
| 2003 | 1 | 14% |
| 2001 | 1 | 3% |
| 2000 | 1 | 4% |
| 1999 | 1 | 5% |
| 1998 | 1 | 8% |
Other parts of the 2021 GMC Sierra 3500
7 complaintsBrakes
5 complaintsEngine
3 complaintsOther or unknown
3 complaintsFuel system
2 complaintsBack-over prevention (rear camera)
1 complaintsBody and structure
1 complaintsTires
1 complaintsVisibility (wipers, defrost, mirrors)
1 complaints
← All problems reported for the 2021 GMC Sierra 3500
About this data. Data from NHTSA (ODI) complaints, recalls, TSBs and investigations, updated Oct 28, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.
To check a specific vehicle for open recalls, use its VIN at nhtsa.gov/recalls. Methodology